This invention pertains generally to radar receivers used in missile guidance systems and particularly to any receiver, such as a monopulse receiver, which incorporates an automatic gain control arrangement.
It is well known in the art that results obtained with an automatic gain control arrangement (referred to hereinafter simply as AGC) used to maintain the level of the output of an amplifier in a missile-borne radar receiver are affected by any substantial change in ambient temperature. Because the active elements in amplifiers of the type used in radar receivers are usually silicon transistors, two characteristic problems are experienced. Firstly, with an input signal of a given level, the level of the AGC varies inversely with ambient temperature. Secondly, even with a constant ambient temperature, the dynamic range (meaning the range of levels of the input signals within which the level of the output, or AGC, signals is linearly related to the level of the input signals) is relatively restricted.
It will be appreciated that it is not feasible in a missile-borne receiver to maintain the ambient temperature of any AGC arrangement at a predetermined level. That is to say, it is not practical to provide so-called constant temperature ovens because of the weight, physical size and power requirements of such ovens.
In flight testing of guided missiles it is necessary, inter alia, to evaluate the performance of the various AGC arrangements in the missile-borne radar receiver. Obviously, then, some way must be devised to eliminate the effects of changes in ambient temperature in such evaluation.